I guess I'll chime in here. I've driven with both of them for extended periods of time and here is my conclusion. The Big Type R is really nice in terms of the grip it offers. If you're the type of person that pushes or pulls the gears into place, and you like holding your shift knob from the side, the Big Type R is for you. It has a great verticle space so you have lots of room to grip the shifter.
The M1 Abrams is more for the type of person who likes to shift with their hand resting on the top of the shift knob. It's a more diverse shift knob seeing as you can also shift it from the side, but your index and pinky will most likely be wanting more grip if you tend to shift often from the side. It really does feel great from the top though.
Also if you're looking for the heaviest shift knob available, the Big Type R is a beast. If you want something still heavy, but slightly more tame, the M1 Abrams is for you!
Let me know if there's anything else I can do for you!
Patrick
Team TWM Performance